Rule preambles

I’m sure I’m forgetting something obvious here, but I thought there was a way to apply a rule to multiple two-noun actions like this?

Instead of inserting something into or throwing something at when the second noun is the waterfall:

Inform just gives a confusing error message (“The part after ‘when’ (or ‘while’) was fine, but the earlier words did not make sense as a description of an action. Looking at this as a list of alternative actions: ‘inserting something into’ was okay; ‘throwing something at’ was okay; so I am unable to place this rule into any rulebook.”) which doesn’t indicate which part was wrong.

I think this works:

Instead of inserting or throwing when the second noun is the waterfall:

though it might break if you have another action whose name begins with “throwing.”

…and you should probably report the confusing error message as a bug.